Solid state motors such as piezoelectric motors have some unique properties. They may be energized proportionately; they may be held in energized condition without significant consumption of energy; they may be operated without significant wear or deterioration; they develop high forces; they respond to energization extremely fast; and, their load/displacement characteristics closely match the requirements of typical fast-response mechanisms.
However, the solid state motor has a relatively small displacement (i.e. elongation). Thus, many applications of the solid state motor require that its displacement be amplified either mechanically or hydraulically to produce a greater displacement of the member which is the subject of the actuation.
A common hydraulic amplifier is a master/slave piston arrangement, such as shown in U.S. Pat. No. 3,648,967, which issued on Mar. 14, 1972. This common arrangement includes a solid state motor in contact with a relatively large diameter piston, which is separated from the relatively smaller diameter piston, which is the ultimate subject of the actuation, by a fluid filled space. The relatively small displacement of the larger piston results in a greater displacement of the smaller piston because the displacement of the smaller piston is equal to the displacement of the larger piston multiplied by the quotient obtained by dividing the surface area of the larger piston in contact with the fluid by the surface area of the smaller piston in contact with the fluid.
One problem with such a master/slave piston arrangement is that it is extremely difficult to prevent fluid from leaking from the fluid filled space into the solid state motor cavity. The present invention is a low cost means for providing amplification while solving the leakage problem. In place of the larger piston has been substituted a deflectable, resilient member.
Therefore, it is an object of the present invention to provide a hydraulic amplifier system including a deflectable, resilient member, a fluid filled space in the pathway of and into which said deflectable, resilient member is deflectable, a subject member adjacent said fluid filled space, and a means for deflecting said deflectable, resilient member into said fluid filled space, wherein deflection of the deflectable, resilient member into the fluid space causes the hydraulic pressure of the fluid to increase which resultingly displaces the subject member from its first position.
Additional objects of the present invention are that the means for deflecting be an electroexpansive module, such as a piezoelectric motor, that the deflectable, resilient member be made of metal, such as SAE 1095 spring steel, that the fluid space be closed (i.e., the fluid does not drain out of the fluid space when the deflectable, resilient member deflects into the fluid space), and that the subject member be a spool valve spring biased to its first position.